1. Field of the Invention
The present invention relates to an image reading device in which an image, recorded in a film, for example, is irradiated with a light beam and the image is read using a line sensor.
2. Description of the Related Art
Conventionally, there is known an image reading device in which a film is intermittently moved along a direction perpendicular to a longitudinal direction of a line sensor, so that an image is read line by line. Namely, while the film is stopped, a light beam outputted from a light source illuminates the film, so that one line image is sensed by the line sensor. After this sensing operation, the film is moved by a predetermined amount by a moving mechanism. The sensing operation and the movement are repeatedly carried out, so that one frame image is read.
In such a reading operation, i.e. a scanning operation, first, the image is scanned with a coarse pitch, so that an exposure measurement is carried out based on image data obtained by this coarse pitch scanning operation, to obtain an optimum exposure time and a color correction coefficient. The optimum exposure time is the ideal period for which electric charges should be accumulated in the line sensor, and the color correction coefficient is used for obtaining a color image having an optimum color balance when the image is reproduced.
In the exposure measurement, the image is coarsely scanned with a uniform pitch over the whole image. Namely, the whole of the image is treated uniformly in order to calculate the optimum exposure time and the color correction coefficient. However, in an image in which a high luminance object is recorded at the center portion thereof, for example, since the optimum exposure time and the color correction coefficient are not calculated with emphases on the object, the object image may not be reproduced with a luminance and color which are desired by the user.